Hyperinsulinemia may increase the concentration of estrogens by decreasing the concentration of SHBG and elevating the concentration of insulin-like growth factor-1 (IGF-1), which can stimulate endometrial cell proliferation by dwindling concentrations of insulin-like growth factor binding protein 1 (IGFBP-1).15Finally, regular physical activity seems to have protective effects on inflammatory processes and oxidative stress, as it raises systemic levels of anti-inflammatory cytokines.16However, the meta-analyses reviewed in the present study do not conclusively support this hypothesis. Here, IGFBP1 is linked to hyperinsulinism.